Over 1-2% of Americans greater than 65 years of age have heart disease. According to the American Heart Association, heart failure is one of the most common causes of hospitalization for patients over 65 years of age in the Western world and as the population ages, this situation will only get worse. Currently, more than 5 million Americans suffer from heart failure. In 2009, the economic cost (direct and indirect) to US society for heart disease was in excess of $37 billion per year. Certain diseases related to heart muscle failure or heart muscle weakening are treatable with drugs or devices such as defibrillators, pacemakers or implanted pumps. However, in heart attacks, when heart muscle cells die, transplantation becomes the only option because cardiomyocyte regeneration in the human heart is generally very limited. Today, unfortunately, there is considerably less heart transplantation tissue available than the current need for transplants. Tens of thousands of hearts could be used each year for transplants but only about 2,000 hearts are available. Chemical biology approaches to embryonic stem cell (ESC) research offers considerable promise for rectifying this problem. However, despite progress, increasing the efficiency of stem or progenitor cells to become human cardiomyocytes has been very challenging. The main problem with increasing the yield of cardiomyocytes is the lack of effective ways to induce ESCs to afford cardiomyocytes involved in cardiogenesis. A critical issue is the low yields of cardiomyocytes from in vitro differentiation processes. An economically viable biotechnological process using readily available and inexpensive differentiation agents is needed. Herein, we propose to use a powerful combination of high content and high throughput cellular assays and dynamic medicinal chemistry to develop pure, easy to make, small molecule "toolbox" compounds to promote the induction of hESCs that will differentiate into cardiomyocytes. A promising new cardiomyocyte differentiation agent (i.e., compound 1) has been identified and refinement and development of this agent is the focus of this proposal. The Specific Aims include: 1) Test compounds structurally related to 1 as inducers of cardiomyocytes in a validated mouse ESC assay and 2) Test potent compounds identified in Aim 1 in a validated human ESC assay for cardiomyocyte differentiation. Based on our encouraging Preliminary Results successful completion of the proposed work will provide an inexpensive toolbox of reagents useful for the induction of cardiomyocytes from human ESCs of utility in a biotechnological sense. Preparation of human cardiomyocytes in this manner will provide large numbers of cardiomyocytes and will be of widespread use to the CRO, biotechnology or Big Pharma industry to help individuals that suffer from heart failure including myocardial infarct as well as to do drug safety tests with human cardiomyocytes to decrease adverse drug-drug interactions and develop safer drugs. PUBLIC HEALTH RELEVANCE: For heart attack victims, stem cell therapy may provide a way to regenerate damaged heart muscle cells. Current therapies are only able to improve heart function. The goal of our work is to use chemical biology to develop small molecule "toolbox" compounds that will stimulate stem cell differentiation and produce cardiomyocytes. Ultimately, the results from this work will provide reagents for use to grow cardiomyocytes for use in a biotechnology process to treat heart disease.